A cluster is a group of JOnAS servers having common properties within a domain. It usually allows to run a J2EE application, or a J2EE module, on the cluster members as if they were a single server. The objective is to achieve applications scalability and high availability.
JOnAS supports several cluster types:
Clusters for Web level load-balancing
Clusters for high availability of Web components
Clusters for EJB level load-balancing
Clusters for high availability of EJB components
Clusters for JMS destination scalability and high availability
Clusters for administration purpose which facilitate management operations like deployment /undeployment.
From the administrator point of view, a cluster represents a single administration target.
Note that a particular JOnAS server may belong to zero, one or more clusters.